In spite of the large amount of experimental and clinical work done on intestinal obstruction, there are still numerous insular concepts of the cause of death, and there are differences of opinion as to treatment. There have been several excellent reviews of the literature during the last few years, and Cooper has recently published an admirable analysis of the situation from the experimental evidence at hand. Since this literature is available, we shall not attempt to review past evidence but shall report the results of our experiments and our deductions as to the manner of treatment likely to be most beneficial for patients having intestinal obstruction. There is general agreement that simple obstruction differs materially from obstruction with strangulation. This study deals only with simple obstruction. There have been three primary purposes in these experiments: (1) to determine the toxicity of the content of obstructed intestine when it is present